For many drilling operations, it is necessary to drill relatively deep wells, thereby requiring longer drill strings and larger traveling blocks. These longer drill strings and larger traveling blocks, in turn, require the use of greater mast heights. To accommodate this requirement, usually mounted drawworks and other drilling equipment are placed on an elevated equipment floor, which is elevated above ground level so as to provide clearance for a relatively tall blow-out prevention apparatus.
In order to accommodate the need for an elevated equipment floor, numerous structures have evolved, but have proven to be deficient in many ways. Most particularly, prior art elevated floor structures have proven to be relatively complex and time consuming to assemble at the drilling site, and, for this reason, are expensive to assemble and use. In many such prior art structures, the elevated floor and then the mast must be constructed and connected together in, essentially, a piece-by-piece operation, very often requiring the use of a crane which thereby increases the expense. Further, when structures are finally erected, the rigging or outfitting of them must be carried out at the elevated level further requiring the use of a crane and additionally complicating the rigging process.
Examples of such prior art structures include those which have a relatively low substructure supporting a tall mast, and the elevated equipment floor is inserted in the mast at a given distance above ground level. Usually, an additional elevated support structure is provided for the drawworks. In such an arrangement, the rigging operation must be carried out at an elevated level requiring the use of cranes and, prior to rigging being able to occur, it is necessary that separate raising operations be carried out for the various portions of the equipment floor. This arrangement, therefore, produces a complex arrangement for constructing the elevated floor, as well as an expensive rigging operation.
It is a desire of the present invention to provide a well drilling apparatus for drilling oil and gas wells or the like, in which the component parts can be assembled horizontally at ground level and then raised to a vertical position where they are operational and in which all of the raising operations can be accomplished with power supplied by a pair of built-in hydraulically driven winches or a pair of built-in dog tail spoolers. It is another desire of the present invention to provide a well drilling apparatus that is modular and can be easily relocated from one site to another without much disassembling.